In a statement, the civil rights organization alleged the fierce grassroots campaigns threatening to derail the standards are being fueled by "far-right propaganda that relies heavily on distortions, outright falsehoods and demonizing conspiracy theories promoted by anti-government extremists."

The national English and math standards developed by an initiative of the National Governors Association and the Council of Chief State School Officers were adopted by the Alabama State School Board in 2010 as part of a wider effort to better prepare students for college or career upon graduation.

The standards have since survived multiple state legislative repeal attempts based on accusations that the state is ceding control over its education system to the federal government.

Those claims were based on the Obama administration's decision in 2009 to make adoption of the Common Core a condition for states seeking certain federal education grants. While Alabama sought one of those grants, its application was not approved.

The SPLC said today that to the Christian Right as well as Tea Party and anti-government activists claim the state-driven effort is actually "Obamacore," a nefarious, left-wing plot to wrest control of education from local school systems and parents through "government indoctrination camps."

"These claims may sound outlandish -- and they are -- but the fact is millions of Americans are absorbing this extremist propaganda, and it's having a very real impact," said Heidi Beirich, director of the SPLC's Intelligence Project.

"These lies are being repeated in churches, legislative hearings and town hall meetings across the country."

The SPLC alleged some opponents, including national groups associated with the billionaire Koch brothers, are exploiting the Common Core in their broader fight against the public education system in an effort to promote the privatization of schools.

"The 50 million children in our nation's public schools, and the dedicated educators who serve them, deserve better than a debate that focuses on falsehoods and demonizes the very idea of public education," said Teaching Tolerance Director Maureen Costello.

"There are legitimate concerns about the Common Core, but those very real issues are being obscured and distorted by the claims of extremists."

The Common Core sets minimum achievement standards for students, telling schools and teachers what lessons students should grasp by each grade. They do not require the use of any particular curriculum, which state school officials say are still determined at the local level.

Initially, 45 U.S. states adopted the standards, but Indiana became the first state to withdraw from the standards in March.